Simultaneous physical, chemical, and microstructural analysis to assess downstream clay soil dispersion with continuous annual use of fertilizers
This study investigates the geochemical effects of four commonly applied chemical fertilizers—sodium chloride (NaCl), calcium sulfate (CaSO₄), ammonium nitrate (NH₄NO₃), and monopotassium phosphate (KH₂PO₄)—on downstream clay soils (DCS) in Qasr-e-Shirin, Iran, following continuous annual use. These...
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| Main Authors: | , , |
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| Format: | Article |
| Language: | English |
| Published: |
Elsevier
2025-09-01
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| Series: | Results in Engineering |
| Subjects: | |
| Online Access: | http://www.sciencedirect.com/science/article/pii/S2590123025025769 |
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| Summary: | This study investigates the geochemical effects of four commonly applied chemical fertilizers—sodium chloride (NaCl), calcium sulfate (CaSO₄), ammonium nitrate (NH₄NO₃), and monopotassium phosphate (KH₂PO₄)—on downstream clay soils (DCS) in Qasr-e-Shirin, Iran, following continuous annual use. These fertilizers are mobilized through irrigation and rainfall, altering the structural integrity of the DCS. Due to constraints in natural soil resources and widespread agricultural drainage interventions, chemically affected DCS is increasingly employed in infrastructure, notably as embankment material for water transfer canals. Such use necessitates rigorous assessment of soil aggregation stability to prevent long-term structural deterioration due to dispersion. To evaluate dispersion potential, DCS was amended with each fertilizer at concentrations of 3%, 5%, 7%, and 10% by dry weight. Dispersion characteristics were examined using a suite of macrostructural and microstructural analyses, including crumb, double hydrometer, pinhole, Sherard, pH, and EC measurements, as well as scanning electron microscopy (SEM). Results demonstrated a concentration-dependent increase in dispersion in previously non-dispersive DCS, with all samples showing potential for structural failure within 180 days. Standard physical and chemical tests, such as Pinhole and Sherard, exhibited reduced sensitivity in detecting dispersion at low fertilizer concentrations and in the presence of monovalent anions. SEM imaging enhanced interpretive accuracy by revealing newly formed voids, weakened particle contacts, and microstructural degradation. These findings underscore the importance of precautionary design when incorporating DCS into embankment construction. |
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| ISSN: | 2590-1230 |